1. Field of the Invention
The present invention relates to dust collecting devices of the type generally known as bag filters, and more particularly it relates to apparatus that includes specific apparatus adapted to shake each bag to remove particles of dust that have collected upon the surface thereof during the filtering operation.
2. Description of the Prior Art
Various arrangements have been developed for shaking or otherwise vibrating the dust collecting elements whereby dust particles accumulating thereon will become dislodged and fall by gravity to a collecting chamber at the bottom of the housing.
A dilemma frequently associated with known shaking devices is that when sufficient shaking is imparted to the bags to remove dust therefrom, the fabric of the bags quickly deteriorates. This has been found to be especially true with filter bags that are formed from synthetic fabrics such as fiberglass, since repeated stretching or elongation of the bags tends to quickly break the fibers of the filter so as to impart a short life thereto. It has been found, however, that filter bags made from synthetic fibers have superior filtering characteristics for conditions that involve high temperature, excess acid or abrasive dust, so the goal of finding suitable shaking means for a bag filter still remains. In a continuing effort to provide apparatus that imparts a suitable motion to the filter bags of a bag filter, vibrators, oscillators and rockers have been constructed after examples set forth by various patents.
In U.S. Pat. Nos. 2,932,362 and 3,955,947 arrangements have been developed whereby a rotary motor is attached to a series of filter bags by means of an eccentric linkage to impart an oscillatory movement to the several bags to produce a shaking and stretching action that removes the collected dust therefrom. While it is recognized that an oscillatory movement may be used to shake dust from the surface of a filter, the agitation promoted by such a movement may not be satisfactory for the removal of dust under all conditions since it simultaneously produces a stretching action that causes deterioration and failure of the filter bags.
Electric vibrators have also been used, however, the amplitude of movement to the bags imparted by such apparatus is insufficient in most cases to jar the more tenacious particles therefrom.